Botanic Superlative: The Coldest Climate Wildflower

Botanic Superlative: The Coldest Climate Wildflower

January 17, 2014
Photo by: Alastair Rae / Wikimedia

When your plants threaten to wilt with the surging summer temperatures, you might offer them an alternative: a cool respite on an arctic slope—tell them you know of a little spot 14,780 feet (4,500 meters) above sea level, in the Swiss Alps. If your hydrangea balks ("No plant could grow there! So high, so cold!"), mention the purple saxifrage (Saxifraga oppositifolia), a plant that grows quite happily in these high snowy peaks. It can't be easy: The ground is free of snow for only two months a year and every night the temperatures drop below zero degrees Celsius. And yet the plant grows, blooming by early May when the snows finally melt. Common in alpine gardens, the purple saxifrage is a small flowering plant that has been discovered growing in record-setting grueling conditions, including in the coldest climates and at one of the highest altitudes in the world. 

The purple saxifrage has been discovered growing in record-setting grueling conditions, including in the coldest climates and at one of the highest altitudes in the world. 

It's quite possible that purple saxifrage is in your garden now, flowering into mid-summer—the alpine wildflower is common in mountainous and arctic regions including northern Britain, the Alps, and even northern Greenland (the most northerly plant locality in the world, on Kaffeklubben Island). It is also the county flower of County Londonderry in Northern Ireland and is very popular in the Scottish Highlands, where its large purple blossoms are a harbinger of spring, blooming on rocky slopes among melting snows. Its flowers are semi-sweet and edible. In 1940, Canadian botanist Nicholas Polunin wrote that the purple saxifrage "must be reckoned among the world's greatest beauties, especially as it stands out in its unusually bleak and desolate surroundings." It's often the only plant growing in polar desert climates. 

The alpine wildflower received its superlative title last June, when Swiss botanist Christan Körner published his discovery of purple saxifrage growing at high altitudes in the Swiss Alps. A statement from Basel University announced: “It is almost a miracle, but at 14,780 feet, at 40 meters below the Dom peak [in the Alps], Saxifraga oppositifolia has been recently discovered. It is the highest-elevation flowering plant that has ever been documented in Europe, and the location is probably the coldest point in the world where a flowering plant has been found." 

S. oppositifolia has evolved adaptive strategies to survive in arctic climates. It prefers to grow on rocks, on northern and eastern slopes, where the sun's heat is mitigated and where water is more abundant. The plant's long roots penetrate far into crevices of the rocks, where winter frosts are less severe and deep water reservoirs can be tapped.

The plant, sometimes considered a floral moss, grows in low cushions that sweep over the rocks. Its leaves are shiny, small, evergreen, and dense. These adaptations help prevent transpiration, or water loss through the plant's stem and leaves. And the leaves have an additional mechanism—like most plants, leaves of the purple saxifrage are covered with surface pores, or stomata, through which water escapes during transpiration. To control water loss, the plant's pores are surrounded by chalk-secreting tissues. Water leaving the leaf dissolves the chalk and deposits it at the stomata. On dry days when evaporation is rapid, the chalk accumulates to form a plug that will prevent water from being released. At night, when evaporation is slow, the slowly-evaporating water dissolves the chalk plug. The chalk, forming like a crystal dusting on the leaves, helps the plant survive in temperatures that plunge to -20.2 degrees F (-29 degrees C).

Seeds are available and the plants are generally zoned for USDA 4 to 9. 

Anna Laurent is a writer and photographer. Her work explores how we look at plants, and how those plants behave.

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